added error middleware, fix broken error res' and uuid usage
added error middleware, fix broken error res' and uuid usage

tyler-johnson/express-pouchdb,tyler-johnson/express-pouchdb,pouchdb/pouchdb-server,tyler-johnson/express-pouchdb,pouchdb/pouchdb-server,nicolasbrugneaux/express-pouchdb,nicolasbrugneaux/express-pouchdb,nicolasbrugneaux/express-pouchdb